Significant research and development efforts are currently directed towards designing and manufacturing nanoscale electronic devices, such as nanoscale memories. Nanoscale electronics promises significant advances, including significantly reduced features sizes and the potential for self-assembly and for other relatively inexpensive, non-photolithography-based fabrication methods. However, the design and manufacture of nanoscale electronic devices present many new challenges.
For instance, nanoscale devices using switching materials such as titanium oxide that show resistive switching behavior have recently been reported. The switching behavior of such devices has been linked to the memristor circuit element theory originally predicted in 1971 by L. O. Chua. The discovery of the memristive behavior in the nanoscale switches has generated significant interest, and there are substantial on-going research efforts to further develop such nanoscale switches and to implement them in various applications. One of the many important potential applications is to use such switching devices as memory units to store digital data, in which an active region is sandwiched between two electrodes. A memory device may be constructed as an array of such switching devices in a crossbar configuration to provide a very high device density. There are, however, technical challenges that have to be addressed in order to make the switching devices useful for actual applications. One significant issue is how to maintain the switching characteristics of the switching devices over multiple ON/OFF cycles to provide a reasonably long operation life.